A Brief History of High-Energy Astronomy: 1965 - 1969

In Reverse Chronological Order

20 Jul 1969
16:18 EST

Neil Armstrong reports back to Mission Control Houston
"The Eagle has landed" -- the
Apollo 11 Lunar Module containing Armstrong and Edwin Aldrin
has landed on the Moon. Shortly thereafter Armstrong becomes the first
human being to step and walk on the Moon.

3 Jul 1969

First ever detection of a cosmic gamma-ray burst (GRB) with
positional information, achieved by the
Vela 5A and Vela 5B satellites: see Strong et
al. 1974, ApJ, 188, L1 for more details about this discovery.

23 May 1969

Co-launch of the
Vela 5A and Vela 5B
satellites to monitor compliance with the Limited Test Ban Treaty of 1963.
Together with the Vela
6A and 6B
satellites, these satellites are often credited with the first discovery
of gamma-ray bursts (GRBs) although it was later realized that the Vela
4A and Vela
4B satellites had actually detected at least one GRB in 1967.

Jan 1969

Publication of the first issue of
Astronomy and Astrophysics, a European journal which `publishes papers
on all aspects of astronomy and astrophysics:
theoretical, observational, and instrumental". This journal was the result
of the merger of five European astronomical journals of
longstanding: Annales d'Astrophysique, Bulletin Astronomique, Bulletin of
the Astronomical Institute of the Netherlands, Journal des Observateurs, and
Zeitschrift fuer Astrophysik, and is now generally regarded as one of the
three premier journals in astronomy.

Launch of a rocket from Johnston Atoll that carried two
proportional counters sensitive to 1.5 to 25 keV X-rays. This
experiment detected several sources, including a spatially extended one
towards the Large Magellanic Cloud, the first X-ray detection of another
Local Group galaxy: see Mark et al., ApJ, 155, L143, 1969 for more
details.

27 Mar 1968

Soviet Cosmonaut Yuri Gagarin is killed in an airplane accident.

1967 - 1968

First Detection of rapidly pulsing radio sources, dubbed pulsars.
These strikingly regular pulses, initially suspected to be caused by
terrestrial interference, then briefly considered to be possible signals
from extraterrestrial life, were within a year agreed to be due to
beamed emission from rapidly rotating neutron stars. Two of the then-known
handful of pulsars were found to lie in the directions of supernovae
remnants (the Crab and Vela Nebulae) in confirmation of Baade and
Zwicky's (1934) hypothesis for the origin of supernovae (q.v.).

7 Sep 1967

First reported detection of the Earth's X-ray airglow by two
proportional counters flown on a Nike-Tomahawk rocket from Tonopah, Nevada.
The team from Lawrence Livermore Lab were conducting a daytime flight to
detect X-rays from Sco X-1 and the Crab Nebula when their experiment
recorded a high count rate which peaked at an altitude of 130 km. Three
weeks later, a flight with similar detectors flown at night detected no
such emission. The researchers correctly interpreted this anomalous emission
as fluorescent emission from nitrogen
and oxygen in the Earth's atmosphere which had been excited by solar X-ray
emission: see Grader et al. 1968, JGR, 73, 7149 for more details about this
discovery.

2 Jul 1967

First ever detection of a cosmic gamma-ray burst (GRB) (albeit with
no positional information), achieved by the Vela
4A and Vela
4B satellites: see Strong et al. 1974, ApJ, 188, L1 for more
details about this discovery.

17 May 1967

Launch of an Aerobee rocket equipped with two proportional counters
flown by a team from the US Naval Research Laboratory. These instruments
detected X-rays from the quasar 3C 273 at a level of about
one-thousandth of the brightest known X-ray source (Sco X-1); see Friedman
and Byram (1967), Science, 158, 257 for more details.

28 Apr 1967

Co-launch of the Vela 4A
and Vela 4B satellites to monitor compliance with the Limited Test Ban
Treaty of 1963. Together with the Vela 5A, Vela 5B and the Vela 6A and 6B satellites,
the Vela satellites made the first discovery of gamma-ray burst sources.

28 Apr 1967

Launch of the Fourth
Octahedral Research Satellite (ORS-4; ERS-18). ORS-4 carried
gamma-ray sensors that were the first to detect the diffuse cosmic
gamma-ray background above 3.0 MeV (the upper limit of Ranger 3, the only
previous gamma-ray detector to observe the gamma-ray background).

27 Jan 1967

A fire in the Apollo 1 capsule during a test on the launch pad kills
three American astronauts: Virgil Grissom, Ed White II, and Roger
Chaffee.

Aug 1966

The position of the X-ray source Sco X-1 is localized to a few arcminutes
(Gursky et al. 1966, ApJ, 146, 310), thereby enabling its optical
counterpart, a blue star with an unusual emission-line spectrum, to be
identified (Sandage et al. 1966, ApJ, 146, 316).

1 Mar 1966

The Soviet spacecraftVenera 3 ceases to send data just as it arrives at Venus. However,
the landing module did descend into the Venusian atmosphere, making this
the first impact or landing of a spacecraft on another planet.

14 Jan 1966

Sergei Korolev, father of the Soviet space program, dies during
surgery.

6 Dec 1965

In a flight of an X-ray telescope suspended on a balloon, a
team from the Goddard Space Flight Center detects an extended X-ray
source at the position of the Coma cluster of galaxies, the first
X-ray detection of a cluster of galaxies: see Boldt et al. 1966, Phys. Rev.
Letters, 17, 447 for more details. In a follow-up paper, Felten et al.
(1966, ApJ, 146, 955) argue (correctly, as it later turned out) that the
X-ray emission comes from a hot (108 K) intergalactic
medium which pervades the entire Coma cluster.

Launch of an Aerobee rocket equipped with two Geiger counters flown
by a team from the US Naval Research Laboratory. These instruments detected
the first discrete X-ray sources identified with extragalactic objects,
namely the elliptical galaxy Messier 87 and the `radio' galaxy Cygnus A, and
also detected the galactic supernova remnant Cassiopia A. They also found
that the previously detected source Cygnus X-1 had varied by a factor of
several compared to its strength 9 months earlier, `the first clear
example of an X-ray variable'; see Byram et al. (1966), Science, 152,
66 for more details.